The Object 685 was a proposed replacement for the PT-76. It competed with two other designs, namely Object 788 and Object 934. The project's notable requirements were to develop a vehicle with a maximum combat weight of 15 tons, armed with a rifled 100-mm gun, an 9K111 "Fagot" anti-tank missile system, and a 12.7 mm machine gun. The project's protection requirements included anti-nuclear features like automatic sealing and air filtration capabilities, and the ability to withstand up to 23 mm AP rounds. Object 788 was disqualified for not including the 9K111 "Fagot" anti-tank missile system, trench-digging equipment, and a water-jet propulsion system. However, both Object 934 and Object 685 managed to pass the initial design evaluation, suggesting that they showed promise despite lacking certain components. It is likely that these designs were later taken into consideration for modifications and improvements to incorporate the missing criteria. Nevertheless, the production was eventually abandoned because they were unable to garner enough interest to continue. Still, later Soviet AFV designs made extensive use of many of the components and design solutions found in Object 934 and Object 685, showing that their potential was recognized and put to good use.

The Object 685 was introduced in Update 1.91 "Night Vision". It is a powerful and versatile vehicle that is well-suited for flanking. It features excellent forward mobility, a 6-second reload cannon, and a sufficient 3BM25 shell. However, its main drawbacks are its subpar survivability, lack of thermal sights, and poor gun depression. Even despite that, the Object 685 remains a good choice for players who prefer a more careful yet aggressive and fast-paced playstyle.